1. Field of the Invention
The invention relates to the process of producing a layout for an integrated circuit. More specifically, the invention relates to a graphical user interface for a cell router that routes interconnections between cells of an integrated circuit, wherein the graphical user interface is usable by both novice and advanced users.
2. Related Art
The process of producing a layout for an integrated circuit involves many operations that are computer intensive. These operations include placing circuit cells and other elements on an integrated circuit floor plan and then routing interconnections between the various elements of the integrated circuit. The process of routing the interconnections between the various elements of the integrated circuit is typically performed by a cell router, such as the cell router incorporated in the Cadabra™ system distributed by Synopsys, Inc. of Mountain View, Calif. A cell router routes connections within a specific cell as opposed to a global router, which routes connections between cells within an integrated circuit. A cell is a collection of devices grouped together to perform a specific function. For example, a cell can be a standard cell from a standard cell library.
A cell router can be viewed as a “black box” that takes a placed cell layout as an input and produces a routed cell layout as an output. Since different applications often require different routing styles, the cell router typically includes setup parameters that can be used to tune the cell routing solver. These parameters can include layer costs and penalties, contact costs and penalties, and the like. A deep understanding of the cell router is required to set the parameters in an optimal manner.
FIG. 1 illustrates a graphical user interface 102 designed for advanced users. Graphical user interface 102 allows a user to adjust, inter alia, the routing costs, wire widths and the snap-to-grid characteristics for different wire types 104. Note that the routing costs are typically a function of the length of the wire.
While graphical user interface 102 allows a user to configure routing parameters within the system, a novice user has insufficient knowledge to be able to successfully set a routing strategy, for example by setting a preference for power routing. This is because setting a preference for power routing (or any other preference) requires a comprehensive understanding of the interactions between the various parameters and how to assign costs for the various wire types 104.
Hence, what is needed is an interface to the cell router that assists the novice user in setting routing parameters in an optimal manner while maintaining the ability for an advanced user to individually set each parameter.